mm: fix proc_dointvec_userhz_jiffies "breakage"
Addresses http://bugzilla.kernel.org/show_bug.cgi?id=9838
On i386, HZ=1000, jiffies_to_clock_t() converts time in a somewhat strange
way from the user's point of view:
# echo 500 >/proc/sys/vm/dirty_writeback_centisecs
# cat /proc/sys/vm/dirty_writeback_centisecs
499
So, we have 5000 jiffies converted to only 499 clock ticks and reported
back.
TICK_NSEC = 999848
ACTHZ = 256039
Keeping in-kernel variable in units passed from userspace will fix issue
of course, but this probably won't be right for every sysctl.
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index 7300ecd..9344547 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -109,8 +109,8 @@
extern unsigned long dirty_background_bytes;
extern int vm_dirty_ratio;
extern unsigned long vm_dirty_bytes;
-extern int dirty_writeback_interval;
-extern int dirty_expire_interval;
+extern unsigned int dirty_writeback_interval;
+extern unsigned int dirty_expire_interval;
extern int vm_highmem_is_dirtyable;
extern int block_dump;
extern int laptop_mode;
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index c5ef44f..2e490a3 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -1010,7 +1010,7 @@
.data = &dirty_expire_interval,
.maxlen = sizeof(dirty_expire_interval),
.mode = 0644,
- .proc_handler = &proc_dointvec_userhz_jiffies,
+ .proc_handler = &proc_dointvec,
},
{
.ctl_name = VM_NR_PDFLUSH_THREADS,
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 6aa92b0..30351f0 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -92,14 +92,14 @@
unsigned long vm_dirty_bytes;
/*
- * The interval between `kupdate'-style writebacks, in jiffies
+ * The interval between `kupdate'-style writebacks
*/
-int dirty_writeback_interval = 5 * HZ;
+unsigned int dirty_writeback_interval = 5 * 100; /* sentiseconds */
/*
- * The longest number of jiffies for which data is allowed to remain dirty
+ * The longest time for which data is allowed to remain dirty
*/
-int dirty_expire_interval = 30 * HZ;
+unsigned int dirty_expire_interval = 30 * 100; /* sentiseconds */
/*
* Flag that makes the machine dump writes/reads and block dirtyings.
@@ -770,9 +770,9 @@
sync_supers();
- oldest_jif = jiffies - dirty_expire_interval;
+ oldest_jif = jiffies - msecs_to_jiffies(dirty_expire_interval);
start_jif = jiffies;
- next_jif = start_jif + dirty_writeback_interval;
+ next_jif = start_jif + msecs_to_jiffies(dirty_writeback_interval * 10);
nr_to_write = global_page_state(NR_FILE_DIRTY) +
global_page_state(NR_UNSTABLE_NFS) +
(inodes_stat.nr_inodes - inodes_stat.nr_unused);
@@ -801,9 +801,10 @@
int dirty_writeback_centisecs_handler(ctl_table *table, int write,
struct file *file, void __user *buffer, size_t *length, loff_t *ppos)
{
- proc_dointvec_userhz_jiffies(table, write, file, buffer, length, ppos);
+ proc_dointvec(table, write, file, buffer, length, ppos);
if (dirty_writeback_interval)
- mod_timer(&wb_timer, jiffies + dirty_writeback_interval);
+ mod_timer(&wb_timer, jiffies +
+ msecs_to_jiffies(dirty_writeback_interval * 10));
else
del_timer(&wb_timer);
return 0;
@@ -905,7 +906,8 @@
{
int shift;
- mod_timer(&wb_timer, jiffies + dirty_writeback_interval);
+ mod_timer(&wb_timer,
+ jiffies + msecs_to_jiffies(dirty_writeback_interval * 10));
writeback_set_ratelimit();
register_cpu_notifier(&ratelimit_nb);